This invention relates to binoculars with automatic focusing mechanisms, and more particularly, to an automatic focusing binocular which displays within the field of vision of the user a light which signals the temporary incapacity of the automatic focusing feature of the binocular.
In a binocular in which light beams from a stationary reflector and a movable reflector are introduced to a focus detection module, in response to an instruction signal from this module, at least one part of an eyepiece in each eyepiece assembly is moved to automatically focus the binocular on an object. This automatic focusing feature is rendered inoperative when the automatic focusing system becomes out of order, or its components become defective. The automatic focusing mechanism also does not function when the binocular is used under conditions which exceed the capacity of the module. This capacity is exceeded when the contrast of light and shadow is extremely low; it is entirely dark within the field of vision; or the image, being intricate, is made up a number of contrasts of light and shadow. When the automatic focusing feature is inoperative in binoculars of the prior art, it is normally impossible to tell whether this inoperative condition is due to a defective system or due to an operational system being used in conditions which exceed its capacity.